The present invention relates generally to microsurgical and opthalmic systems and more particularly to an illumination system for providing controlled intensity light at the surgical situs.
In microsurgical systems, such as ophthalmic systems and vitrectomy systems, it is common to provide a source of illumination which can be coupled to a fiber optic cable or to a fiber optic microsurgical illumination instrument, in order to provide light at the surgical situs during surgery. Fiber optic cables are often used for this purpose as they can be made very thin and flexible and are well adapted for inserting directly into the tissue or organ being operated on. Lamps with electronic dimmer circuits are frequently used as the source of illumination to which the fiber optic cable is optically connected.
There are at least two drawbacks with conventional microsurgical illumination systems of this type. One drawback is that, when dimming the lamp using an electronic dimmer circuit, the color temperature of the illumination changes, typically from a comparatively white light to an orange or red light as the light is dimmed. This change in color may be undesirable, since the color of the illuminated tissue or organ is often used for diagnostic purposes. Accordingly, the inability to maintain a constant color temperature illumination is a drawback with conventional illumination systems.
Another drawback is encountered when the lamp fails during surgery. Conventional systems make provisions for this possibility by employing an auxiliary light source which can be manually turned on in the event of a primary light source failure. Commonly, the auxiliary light source is a separate light source with a separate optical coupler for attachment to the fiber optic cable. In order to use such a system, the fiber optic cable must be disconnected from the primary light source coupler and then reconnected to the auxiliary coupler, while at the same time the auxiliary light source must be turned on. Of course, this takes time to accomplish and requires the surgeons and nursing staff to be familiar with the auxiliary light source connection procedure and use.
Aside from the inconvenience, it is considered undesirable to disconnect the fiber optic cable from one optical coupler in order to connect it to the other during surgery, since the fiber optic cable is usually sterilized and the sterile field should not be broken by disconnecting the cable. Also, replacing the burned out lamp is not considered to be a viable alternative because it is time consuming and the bulb will still be quite hot. Additionally, replacement of a burned out lamp may be further complicated if the operating room has been darkened to facilitate a particular surgical procedure.
In order to overcome these drawbacks and to provide an improved illumination system for microsurgical uses, the present invention provides a movable multiple lamp system with an illumination directing mirror which operates automatically when the primary lamp fails. Current flow through the primary lamp is continually monitored so that changeover to the auxiliary lamp occurs quickly and automatically. The lamps are mounted on a movable carriage which may be remotely controlled to move the lamps toward and away from the optical coupler to which the fiber optic cable is attached. In this fashion, the intensity of the illumination supplied to the optical port of the optical coupler can be remotely controlled without the need to dim the lamps electrically. This ensures that the color temperature of the lamps remains substantially constant.
In summary, the invention comprises an illumination system for a microsurgical apparatus which comprises a base and a lamp carriage mounted on the base for movement relative to the base. A lamp or lamp system is carried on the lamp carriage for providing illumination and a fiber optic coupler is disposed on the base for coupling to a fiber optic microsurgical illumination instrument. The fiber optic coupler has an optical port positioned to receive illumination from the lamp or lamp system. A means is coupled to the carriage for moving the carriage selectively toward and away from the coupler to thereby control the intensity of the illumination entering the optical port. A pneumatic drive cylinder may be employed for this purpose and the carriage may be provided with at least one rail mounted on the base for assisting or confining movement of the carriage in a linear direction.
Further in accordance with the invention, there is provided an illumination system comprising at least two lamps supported on the carriage or base for providing illumination. The system further comprises an illumination controlling mechanism supported on the base for selectively causing the illumination from either of the lamps to illuminate the optical port. The illumination controlling mechanism includes an illumination directing means such as a mirror for selectively directing the illumination from either of the lamps towards the optical port. The controlling means is actuated by a mechanism for sensing when one of the lamps is not providing illumination; the mechanism operates by automatically causing the controlling means to cause the second lamp to illuminate the optical port. Preferably, the mirror is movable from a first position whereby a first one of the lamps illuminates the optical port, to a second position whereby a second one of the lamps illuminates the optical port. Failure of the first lamp is sensed by monitoring the electrical current flow through the lamp using a sensor, such as a Hall effect sensor. The lamps are preferably a constant color temperature lamp, such as a quartz halogen lamp of the type found in slide projectors.